Phase rotation for preambles within multiple user, multiple access, and/or MIMO wireless communications

ABSTRACT

Phase rotation for preambles within multiple user, multiple access, and/or MIMO wireless communications. An appropriately designed phase rotation vector and/or appropriately designed cyclic shift delays (CSDs) are applied to respective sub-band components of the preamble. With appropriately designed CSDs, certain fields within the preamble are not modified. For example, a legacy short training field (L-STF) of the preamble is not changed when using appropriately designed CSDs. The respective CSDs may be implemented as integer multiples of a common CSD (e.g., 0×CSD, 1×CSD, 2×CSD, etc. such that one of the values of such a CSD vector may be zero [0], another may be the common CSD itself, etc.). Also, by employing an appropriately designed phase rotation vector and integer multiples of a CSD to a preamble, the respective peak to average power ratio (PAPR) between different respective fields within the preamble may be minimized.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS Provisional Priority Claims

The present U.S. Utility patent application claims priority pursuant to 35 U.S.C. §119(e) to the following U.S. Provisional Patent Application which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility Patent Application for all purposes:

1. U.S. Provisional Application Ser. No. 61/378,769, entitled “Phase rotation for preambles within multiple user, multiple access, and/or MIMO wireless communications,” (Attorney Docket No. BP22244), filed 08-31-2010, pending.

INCORPORATION BY REFERENCE

The following IEEE standards are hereby incorporated herein by reference in their entirety and are made part of the present U.S. Utility Patent Application for all purposes:

1. IEEE Std 802.11™-2007, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” IEEE Computer Society, IEEE Std 802.11™-2007, (Revision of IEEE Std 802.11-1999), 1233 pages.

2. IEEE Std 802.11n™—2009, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications; Amendment 5: Enhancements for Higher Throughput,” IEEE Computer Society, IEEE Std 802.11n™-2009, (Amendment to IEEE Std 802.11™-2007 as amended by IEEE Std 802.11k™-2008, IEEE Std 802.11r™-2008, IEEE Std 802.11y™-2008, and IEEE Std 802.11r™-2009), 536 pages.

3. IEEE P802.11ac™/D1.1, August 2011, “Draft STANDARD for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Amendment 5: Enhancements for Very High Throughput for Operation in Bands below 6 GHz,” Prepared by the 802.11 Working Group of the 802 Committee, 297 total pages (pp. i-xxiii, 1-274).

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention relates generally to communication systems; and, more particularly, it relates to phase rotation for preambles within multiple user, multiple access, and/or MIMO wireless communications.

2. Description of Related Art

Communication systems are known to support wireless and wire lined communications between wireless and/or wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11x, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof.

Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, et cetera communicates directly or indirectly with other wireless communication devices. For direct communications (also known as point-to-point communications), the participating wireless communication devices tune their receivers and transmitters to the same channel or channels (e.g., one of the plurality of radio frequency (RF) carriers of the wireless communication system) and communicate over that channel(s). For indirect wireless communications, each wireless communication device communicates directly with an associated base station (e.g., for cellular services) and/or an associated access point (e.g., for an in-home or in-building wireless network) via an assigned channel. To complete a communication connection between the wireless communication devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, via the public switch telephone network, via the Internet, and/or via some other wide area network.

For each wireless communication device to participate in wireless communications, it includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). As is known, the receiver is coupled to the antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage, and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The one or more intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard.

As is also known, the transmitter includes a data modulation stage, one or more intermediate frequency stages, and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier amplifies the RF signals prior to transmission via an antenna.

Typically, the transmitter will include one antenna for transmitting the RF signals, which are received by a single antenna, or multiple antennae (alternatively, antennas), of a receiver. When the receiver includes two or more antennae, the receiver will select one of them to receive the incoming RF signals. In this instance, the wireless communication between the transmitter and receiver is a single-output-single-input (SISO) communication, even if the receiver includes multiple antennae that are used as diversity antennae (i.e., selecting one of them to receive the incoming RF signals). For SISO wireless communications, a transceiver includes one transmitter and one receiver. Currently, most wireless local area networks (WLAN) that are IEEE 802.11, 802.11a, 802.11b, or 802.11g employ SISO wireless communications.

Other types of wireless communications include single-input-multiple-output (SIMO), multiple-input-single-output (MISO), and multiple-input-multiple-output (MIMO). In a SIMO wireless communication, a single transmitter processes data into radio frequency signals that are transmitted to a receiver. The receiver includes two or more antennae and two or more receiver paths. Each of the antennae receives the RF signals and provides them to a corresponding receiver path (e.g., LNA, down conversion module, filters, and ADCs). Each of the receiver paths processes the received RF signals to produce digital signals, which are combined and then processed to recapture the transmitted data.

For a multiple-input-single-output (MISO) wireless communication, the transmitter includes two or more transmission paths (e.g., digital to analog converter, filters, up-conversion module, and a power amplifier) that each converts a corresponding portion of baseband signals into RF signals, which are transmitted via corresponding antennae to a receiver. The receiver includes a single receiver path that receives the multiple RF signals from the transmitter. In this instance, the receiver uses beam forming to combine the multiple RF signals into one signal for processing.

For a multiple-input-multiple-output (MIMO) wireless communication, the transmitter and receiver each include multiple paths. In such a communication, the transmitter parallel processes data using a spatial and time encoding function to produce two or more streams of data. The transmitter includes multiple transmission paths to convert each stream of data into multiple RF signals. The receiver receives the multiple RF signals via multiple receiver paths that recapture the streams of data utilizing a spatial and time decoding function. The recaptured streams of data are combined and subsequently processed to recover the original data.

With the various types of wireless communications (e.g., SISO, MISO, SIMO, and MIMO), it would be desirable to use one or more types of wireless communications to enhance data throughput within a WLAN. For example, high data rates can be achieved with MIMO communications in comparison to SISO communications. However, most WLAN include legacy wireless communication devices (i.e., devices that are compliant with an older version of a wireless communication standard). As such, a transmitter capable of MIMO wireless communications should also be backward compatible with legacy devices to function in a majority of existing WLANs.

Therefore, a need exists for a WLAN device that is capable of high data throughput and is backward compatible with legacy devices.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating an embodiment of a wireless communication system.

FIG. 2 is a diagram illustrating an embodiment of a wireless communication device.

FIG. 3 is a diagram illustrating an embodiment of a radio frequency (RF) transmitter.

FIG. 4 is a diagram illustrating an embodiment of an RF receiver.

FIG. 5 is a diagram illustrating an embodiment of a method for baseband processing of data.

FIG. 6 is a diagram illustrating an embodiment of a method that further defines Step 120 of FIG. 5.

FIGS. 7-9 are diagrams illustrating various embodiments for encoding the scrambled data.

FIGS. 10A and 10B are diagrams illustrating embodiments of a radio transmitter.

FIGS. 11A and 11B are diagrams illustrating embodiments of a radio receiver.

FIG. 12 is a diagram illustrating an embodiment of an access point (AP) and multiple wireless local area network (WLAN) devices operating according to one or more various aspects and/or embodiments of the invention.

FIG. 13 is a diagram illustrating an embodiment of a wireless communication device, and clusters, as may be employed for supporting communications with at least one additional wireless communication device.

FIG. 14 is a diagram illustrating an embodiment of phase rotation on a preamble as may be performed within one or more wireless communication devices.

FIG. 15 is a diagram illustrating an embodiment of a comparison of peak to average power ratio (PAPR) across various fields of a packet using various phase rotation vectors on frames of various bandwidths.

FIG. 16 is a diagram illustrating an embodiment of a complementary cumulative density (or distribution) function (CCDF) of instantaneous power (P_(inst)) for the L-SIG field.

FIG. 17 is a diagram illustrating an alternative embodiment of phase rotation on a preamble as may be performed within one or more wireless communication devices.

FIG. 18 is a diagram illustrating another embodiment of phase rotation on a preamble as may be performed within one or more wireless communication devices.

FIG. 19 is a diagram illustrating another embodiment of a comparison of PAPR across various fields of a packet using various phase rotation vectors on frames of various bandwidths.

FIG. 20 is a diagram illustrating another embodiment of a CCDF of P_(inst) for the L-SIG field.

FIG. 21 is a diagram illustrating another embodiment of a CCDF of P_(inst) for the L-SIG field, and particularly, using 4× oversampling.

FIG. 22 is a diagram illustrating another embodiment of a comparison of PAPR across various fields of a packet using various phase rotation vectors on frames of various bandwidths.

FIG. 23 is a diagram illustrating another embodiment of a CCDF of P_(inst) for the L-SIG field, and particularly, using 4× oversampling.

FIG. 24 is a diagram illustrating an embodiment of Gaussian fit of a time-domain (t-dom) signal.

FIG. 25 is a diagram illustrating an embodiment of a method for operating one or more wireless communication devices.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a diagram illustrating an embodiment of a wireless communication system 10 that includes a plurality of base stations and/or access points 12-16, a plurality of wireless communication devices 18-32 and a network hardware component 34. The wireless communication devices 18-32 may be laptop host computers 18 and 26, personal digital assistant hosts 20 and 30, personal computer hosts 24 and 32 and/or cellular telephone hosts 22 and 28. The details of an embodiment of such wireless communication devices are described in greater detail with reference to FIG. 2.

The base stations (BSs) or access points (APs) 12-16 are operably coupled to the network hardware 34 via local area network connections 36, 38 and 40. The network hardware 34, which may be a router, switch, bridge, modem, system controller, etc. provides a wide area network connection 42 for the communication system 10. Each of the base stations or access points 12-16 has an associated antenna or antenna array to communicate with the wireless communication devices in its area. Typically, the wireless communication devices register with a particular base station or access point 12-14 to receive services from the communication system 10. For direct connections (i.e., point-to-point communications), wireless communication devices communicate directly via an allocated channel.

Typically, base stations are used for cellular telephone systems (e.g., advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), Enhanced Data rates for GSM Evolution (EDGE), General Packet Radio Service (GPRS), high-speed downlink packet access (HSDPA), high-speed uplink packet access (HSUPA and/or variations thereof) and like-type systems, while access points are used for in-home or in-building wireless networks (e.g., IEEE 802.11, Bluetooth, ZigBee, any other type of radio frequency based network protocol and/or variations thereof). Regardless of the particular type of communication system, each wireless communication device includes a built-in radio and/or is coupled to a radio. Such wireless communication devices may operate in accordance with the various aspects of the invention as presented herein to enhance performance, reduce costs, reduce size, and/or enhance broadband applications.

FIG. 2 is a diagram illustrating an embodiment of a wireless communication device that includes the host device 18-32 and an associated radio 60. For cellular telephone hosts, the radio 60 is a built-in component. For personal digital assistants hosts, laptop hosts, and/or personal computer hosts, the radio 60 may be built-in or an externally coupled component. For access points or base stations, the components are typically housed in a single structure.

As illustrated, the host device 18-32 includes a processing module 50, memory 52, radio interface 54, input interface 58 and output interface 56. The processing module 50 and memory 52 execute the corresponding instructions that are typically done by the host device. For example, for a cellular telephone host device, the processing module 50 performs the corresponding communication functions in accordance with a particular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to the radio 60. For data received from the radio 60 (e.g., inbound data), the radio interface 54 provides the data to the processing module 50 for further processing and/or routing to the output interface 56. The output interface 56 provides connectivity to an output display device such as a display, monitor, speakers, et cetera such that the received data may be displayed. The radio interface 54 also provides data from the processing module 50 to the radio 60. The processing module 50 may receive the outbound data from an input device such as a keyboard, keypad, microphone, et cetera via the input interface 58 or generate the data itself. For data received via the input interface 58, the processing module 50 may perform a corresponding host function on the data and/or route it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, a baseband processing module 64, memory 66, a plurality of radio frequency (RF) transmitters 68-72, a transmit/receive (T/R) module 74, a plurality of antennae 82-86, a plurality of RF receivers 76-80, and a local oscillation module 100. The baseband processing module 64, in combination with operational instructions stored in memory 66, execute digital receiver functions and digital transmitter functions, respectively. The digital receiver functions, as will be described in greater detail with reference to FIG. 11B, include, but are not limited to, digital intermediate frequency to baseband conversion, demodulation, constellation demapping, decoding, de-interleaving, fast Fourier transform, cyclic prefix removal, space and time decoding, and/or descrambling. The digital transmitter functions, as will be described in greater detail with reference to later Figures, include, but are not limited to, scrambling, encoding, interleaving, constellation mapping, modulation, inverse fast Fourier transform, cyclic prefix addition, space and time encoding, and/or digital baseband to IF conversion. The baseband processing modules 64 may be implemented using one or more processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The memory 66 may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. Note that when the processing module 64 implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory storing the corresponding operational instructions is embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry.

In operation, the radio 60 receives outbound data 88 from the host device via the host interface 62. The baseband processing module 64 receives the outbound data 88 and, based on a mode selection signal 102, produces one or more outbound symbol streams 90. The mode selection signal 102 will indicate a particular mode as are illustrated in the mode selection tables, which appear at the end of the detailed discussion. For example, the mode selection signal 102, with reference to table 1 may indicate a frequency band of 2.4 GHz or 5 GHz, a channel bandwidth of 20 or 22 MHz (e.g., channels of 20 or 22 MHz width) and a maximum bit rate of 54 megabits-per-second. In other embodiments, the channel bandwidth may extend up to 1.28 GHz or wider with supported maximum bit rates extending to 1 gigabit-per-second or greater. In this general category, the mode selection signal will further indicate a particular rate ranging from 1 megabit-per-second to 54 megabits-per-second. In addition, the mode selection signal will indicate a particular type of modulation, which includes, but is not limited to, Barker Code Modulation, BPSK, QPSK, CCK, 16 QAM and/or 64 QAM. As is further illustrated in table 1, a code rate is supplied as well as number of coded bits per subcarrier (NBPSC), coded bits per OFDM symbol (NCBPS), data bits per OFDM symbol (NDBPS).

The mode selection signal may also indicate a particular channelization for the corresponding mode which for the information in table 1 is illustrated in table 2. As shown, table 2 includes a channel number and corresponding center frequency. The mode select signal may further indicate a power spectral density mask value which for table 1 is illustrated in table 3. The mode select signal may alternatively indicate rates within table 4 that has a 5 GHz frequency band, 20 MHz channel bandwidth and a maximum bit rate of 54 megabits-per-second. If this is the particular mode select, the channelization is illustrated in table 5. As a further alternative, the mode select signal 102 may indicate a 2.4 GHz frequency band, 20 MHz channels and a maximum bit rate of 192 megabits-per-second as illustrated in table 6. In table 6, a number of antennae may be utilized to achieve the higher bit rates. In this instance, the mode select would further indicate the number of antennae to be utilized. Table 7 illustrates the channelization for the set-up of table 6. Table 8 illustrates yet another mode option where the frequency band is 2.4 GHz, the channel bandwidth is 20 MHz and the maximum bit rate is 192 megabits-per-second. The corresponding table 8 includes various bit rates ranging from 12 megabits-per-second to 216 megabits-per-second utilizing 2-4 antennae and a spatial time encoding rate as indicated. Table 9 illustrates the channelization for table 8. The mode select signal 102 may further indicate a particular operating mode as illustrated in table 10, which corresponds to a 5 GHz frequency band having 40 MHz frequency band having 40 MHz channels and a maximum bit rate of 486 megabits-per-second. As shown in table 10, the bit rate may range from 13.5 megabits-per-second to 486 megabits-per-second utilizing 1-4 antennae and a corresponding spatial time code rate. Table 10 further illustrates a particular modulation scheme code rate and NBPSC values. Table 11 provides the power spectral density mask for table 10 and table 12 provides the channelization for table 10.

It is of course noted that other types of channels, having different bandwidths, may be employed in other embodiments without departing from the scope and spirit of the invention. For example, various other channels such as those having 80 MHz, 120 MHz, and/or 160 MHz of bandwidth may alternatively be employed such as in accordance with IEEE Task Group ac (TGac VHTL6).

The baseband processing module 64, based on the mode selection signal 102 produces the one or more outbound symbol streams 90, as will be further described with reference to FIGS. 5-9 from the output data 88. For example, if the mode selection signal 102 indicates that a single transmit antenna is being utilized for the particular mode that has been selected, the baseband processing module 64 will produce a single outbound symbol stream 90. Alternatively, if the mode select signal indicates 2, 3 or 4 antennae, the baseband processing module 64 will produce 2, 3 or 4 outbound symbol streams 90 corresponding to the number of antennae from the output data 88.

Depending on the number of outbound streams 90 produced by the baseband module 64, a corresponding number of the RF transmitters 68-72 will be enabled to convert the outbound symbol streams 90 into outbound RF signals 92. The implementation of the RF transmitters 68-72 will be further described with reference to FIG. 3. The transmit/receive module 74 receives the outbound RF signals 92 and provides each outbound RF signal to a corresponding antenna 82-86.

When the radio 60 is in the receive mode, the transmit/receive module 74 receives one or more inbound RF signals via the antennae 82-86. The T/R module 74 provides the inbound RF signals 94 to one or more RF receivers 76-80. The RF receiver 76-80, which will be described in greater detail with reference to FIG. 4, converts the inbound RF signals 94 into a corresponding number of inbound symbol streams 96. The number of inbound symbol streams 96 will correspond to the particular mode in which the data was received (recall that the mode may be any one of the modes illustrated in tables 1-12). The baseband processing module 64 receives the inbound symbol streams 90 and converts them into inbound data 98, which is provided to the host device 18-32 via the host interface 62.

In one embodiment of radio 60 it includes a transmitter and a receiver. The transmitter may include a MAC module, a PLCP module, and a PMD module. The Medium Access Control (MAC) module, which may be implemented with the processing module 64, is operably coupled to convert a MAC Service Data Unit (MSDU) into a MAC Protocol Data Unit (MPDU) in accordance with a WLAN protocol. The Physical Layer Convergence Procedure (PLCP) Module, which may be implemented in the processing module 64, is operably coupled to convert the MPDU into a PLCP Protocol Data Unit (PPDU) in accordance with the WLAN protocol. The Physical Medium Dependent (PMD) module is operably coupled to convert the PPDU into a plurality of radio frequency (RF) signals in accordance with one of a plurality of operating modes of the WLAN protocol, wherein the plurality of operating modes includes multiple input and multiple output combinations.

An embodiment of the Physical Medium Dependent (PMD) module, which will be described in greater detail with reference to FIGS. 10A and 10B, includes an error protection module, a demultiplexing module, and a plurality of direction conversion modules. The error protection module, which may be implemented in the processing module 64, is operably coupled to restructure a PPDU (PLCP (Physical Layer Convergence Procedure) Protocol Data Unit) to reduce transmission errors producing error protected data. The demultiplexing module is operably coupled to divide the error protected data into a plurality of error protected data streams The plurality of direct conversion modules is operably coupled to convert the plurality of error protected data streams into a plurality of radio frequency (RF) signals.

As one of average skill in the art will appreciate, the wireless communication device of FIG. 2 may be implemented using one or more integrated circuits. For example, the host device may be implemented on one integrated circuit, the baseband processing module 64 and memory 66 may be implemented on a second integrated circuit, and the remaining components of the radio 60, less the antennae 82-86, may be implemented on a third integrated circuit. As an alternate example, the radio 60 may be implemented on a single integrated circuit. As yet another example, the processing module 50 of the host device and the baseband processing module 64 may be a common processing device implemented on a single integrated circuit. Further, the memory 52 and memory 66 may be implemented on a single integrated circuit and/or on the same integrated circuit as the common processing modules of processing module 50 and the baseband processing module 64.

FIG. 3 is a diagram illustrating an embodiment of a radio frequency (RF) transmitter 68-72, or RF front-end, of the WLAN transmitter. The RF transmitter 68-72 includes a digital filter and up-sampling module 75, a digital-to-analog conversion module 77, an analog filter 79, and up-conversion module 81, a power amplifier 83 and a RF filter 85. The digital filter and up-sampling module 75 receives one of the outbound symbol streams 90 and digitally filters it and then up-samples the rate of the symbol streams to a desired rate to produce the filtered symbol streams 87. The digital-to-analog conversion module 77 converts the filtered symbols 87 into analog signals 89. The analog signals may include an in-phase component and a quadrature component.

The analog filter 79 filters the analog signals 89 to produce filtered analog signals 91. The up-conversion module 81, which may include a pair of mixers and a filter, mixes the filtered analog signals 91 with a local oscillation 93, which is produced by local oscillation module 100, to produce high frequency signals 95. The frequency of the high frequency signals 95 corresponds to the frequency of the outbound RF signals 92.

The power amplifier 83 amplifies the high frequency signals 95 to produce amplified high frequency signals 97. The RF filter 85, which may be a high frequency band-pass filter, filters the amplified high frequency signals 97 to produce the desired output RF signals 92.

As one of average skill in the art will appreciate, each of the radio frequency transmitters 68-72 will include a similar architecture as illustrated in FIG. 3 and further include a shut-down mechanism such that when the particular radio frequency transmitter is not required, it is disabled in such a manner that it does not produce interfering signals and/or noise.

FIG. 4 is a diagram illustrating an embodiment of an RF receiver. This may depict any one of the RF receivers 76-80. In this embodiment, each of the RF receivers 76-80 includes an RF filter 101, a low noise amplifier (LNA) 103, a programmable gain amplifier (PGA) 105, a down-conversion module 107, an analog filter 109, an analog-to-digital conversion module 111 and a digital filter and down-sampling module 113. The RF filter 101, which may be a high frequency band-pass filter, receives the inbound RF signals 94 and filters them to produce filtered inbound RF signals. The low noise amplifier 103 amplifies the filtered inbound RF signals 94 based on a gain setting and provides the amplified signals to the programmable gain amplifier 105. The programmable gain amplifier further amplifies the inbound RF signals 94 before providing them to the down-conversion module 107.

The down-conversion module 107 includes a pair of mixers, a summation module, and a filter to mix the inbound RF signals with a local oscillation (LO) that is provided by the local oscillation module to produce analog baseband signals. The analog filter 109 filters the analog baseband signals and provides them to the analog-to-digital conversion module 111 which converts them into a digital signal. The digital filter and down-sampling module 113 filters the digital signals and then adjusts the sampling rate to produce the digital samples (corresponding to the inbound symbol streams 96).

FIG. 5 is a diagram illustrating an embodiment of a method for baseband processing of data. This diagram shows a method for converting outbound data 88 into one or more outbound symbol streams 90 by the baseband processing module 64. The process begins at Step 110 where the baseband processing module receives the outbound data 88 and a mode selection signal 102. The mode selection signal may indicate any one of the various modes of operation as indicated in tables 1-12. The process then proceeds to Step 112 where the baseband processing module scrambles the data in accordance with a pseudo random sequence to produce scrambled data. Note that the pseudo random sequence may be generated from a feedback shift register with the generator polynomial of S(x)=x⁷+x⁴+1.

The process then proceeds to Step 114 where the baseband processing module selects one of a plurality of encoding modes based on the mode selection signal. The process then proceeds to Step 116 where the baseband processing module encodes the scrambled data in accordance with a selected encoding mode to produce encoded data. The encoding may be done utilizing any one or more a variety of coding schemes (e.g., convolutional coding, Reed-Solomon (RS) coding, turbo coding, turbo trellis coded modulation (TTCM) coding, LDPC (Low Density Parity Check) coding, etc.).

The process then proceeds to Step 118 where the baseband processing module determines a number of transmit streams based on the mode select signal. For example, the mode select signal will select a particular mode which indicates that 1, 2, 3, 4 or more antennae may be utilized for the transmission. Accordingly, the number of transmit streams will correspond to the number of antennae indicated by the mode select signal. The process then proceeds to Step 120 where the baseband processing module converts the encoded data into streams of symbols in accordance with the number of transmit streams in the mode select signal. This step will be described in greater detail with reference to FIG. 6.

FIG. 6 is a diagram illustrating an embodiment of a method that further defines Step 120 of FIG. 5. This diagram shows a method performed by the baseband processing module to convert the encoded data into streams of symbols in accordance with the number of transmit streams and the mode select signal. Such processing begins at Step 122 where the baseband processing module interleaves the encoded data over multiple symbols and subcarriers of a channel to produce interleaved data. In general, the interleaving process is designed to spread the encoded data over multiple symbols and transmit streams. This allows improved detection and error correction capability at the receiver. In one embodiment, the interleaving process will follow the IEEE 802.11(a) or (g) standard for backward compatible modes. For higher performance modes (e.g., IEEE 802.11(n), the interleaving will also be done over multiple transmit paths or streams.

The process then proceeds to Step 124 where the baseband processing module demultiplexes the interleaved data into a number of parallel streams of interleaved data. The number of parallel streams corresponds to the number of transmit streams, which in turn corresponds to the number of antennae indicated by the particular mode being utilized. The process then continues to Steps 126 and 128, where for each of the parallel streams of interleaved data, the baseband processing module maps the interleaved data into a quadrature amplitude modulated (QAM) symbol to produce frequency domain symbols at Step 126. At Step 128, the baseband processing module converts the frequency domain symbols into time domain symbols, which may be done utilizing an inverse fast Fourier transform. The conversion of the frequency domain symbols into the time domain symbols may further include adding a cyclic prefix to allow removal of intersymbol interference at the receiver. Note that the length of the inverse fast Fourier transform and cyclic prefix are defined in the mode tables of tables 1-12. In general, a 64-point inverse fast Fourier transform is employed for 20 MHz channels and 128-point inverse fast Fourier transform is employed for 40 MHz channels.

The process then proceeds to Step 130 where the baseband processing module space and time encodes the time domain symbols for each of the parallel streams of interleaved data to produce the streams of symbols. In one embodiment, the space and time encoding may be done by space and time encoding the time domain symbols of the parallel streams of interleaved data into a corresponding number of streams of symbols utilizing an encoding matrix. Alternatively, the space and time encoding may be done by space and time encoding the time domain symbols of M-parallel streams of interleaved data into P-streams of symbols utilizing the encoding matrix, where P=2M In one embodiment the encoding matrix may comprise a form of:

$\quad\begin{bmatrix} C_{1} & C_{2} & C_{3} & C_{4} & \ldots & C_{{2M} - 1} & C_{2M} \\ {- C_{2}^{*}} & C_{1}^{*} & {- C_{4}^{*}} & C_{3}^{*} & \ldots & {- C_{2M}^{*}} & C_{{2M} - 1} \end{bmatrix}$

The number of rows of the encoding matrix corresponds to M and the number of columns of the encoding matrix corresponds to P. The particular symbol values of the constants within the encoding matrix may be real or imaginary numbers.

FIGS. 7-9 are diagrams illustrating various embodiments for encoding the scrambled data.

FIG. 7 is a diagram of one method that may be utilized by the baseband processing module to encode the scrambled data at Step 116 of FIG. 5. In this method, the encoding of FIG. 7 may include an optional Step 144 where the baseband processing module may optionally perform encoding with an outer Reed-Solomon (RS) code to produce RS encoded data. It is noted that Step 144 may be conducted in parallel with Step 140 described below.

Also, the process continues at Step 140 where the baseband processing module performs a convolutional encoding with a 64 state code and generator polynomials of G₀=133₈ and G₁=171₈ on the scrambled data (that may or may not have undergone RS encoding) to produce convolutional encoded data. The process then proceeds to Step 142 where the baseband processing module punctures the convolutional encoded data at one of a plurality of rates in accordance with the mode selection signal to produce the encoded data. Note that the puncture rates may include ½, ⅔ and/or ¾, or any rate as specified in tables 1-12. Note that, for a particular, mode, the rate may be selected for backward compatibility with IEEE 802.11(a), IEEE 802.11(g), or IEEE 802.11(n) rate requirements.

FIG. 8 is a diagram of another encoding method that may be utilized by the baseband processing module to encode the scrambled data at Step 116 of FIG. 5. In this embodiment, the encoding of FIG. 8 may include an optional Step 148 where the baseband processing module may optionally perform encoding with an outer RS code to produce RS encoded data. It is noted that Step 148 may be conducted in parallel with Step 146 described below.

The method then continues at Step 146 where the baseband processing module encodes the scrambled data (that may or may not have undergone RS encoding) in accordance with a complimentary code keying (CCK) code to produce the encoded data. This may be done in accordance with IEEE 802.11(b) specifications, IEEE 802.11(g), and/or IEEE 802.11(n) specifications.

FIG. 9 is a diagram of yet another method for encoding the scrambled data at Step 116, which may be performed by the baseband processing module. In this embodiment, the encoding of FIG. 9 may include an optional Step 154 where the baseband processing module may optionally perform encoding with an outer RS code to produce RS encoded data.

Then, in some embodiments, the process continues at Step 150 where the baseband processing module performs LDPC (Low Density Parity Check) coding on the scrambled data (that may or may not have undergone RS encoding) to produce LDPC coded bits. Alternatively, the Step 150 may operate by performing convolutional encoding with a 256 state code and generator polynomials of G₀=561₈ and G₁=753₈ on the scrambled data the scrambled data (that may or may not have undergone RS encoding) to produce convolutional encoded data. The process then proceeds to Step 152 where the baseband processing module punctures the convolutional encoded data at one of the plurality of rates in accordance with a mode selection signal to produce encoded data. Note that the puncture rate is indicated in the tables 1-12 for the corresponding mode.

The encoding of FIG. 9 may further include the optional Step 154 where the baseband processing module combines the convolutional encoding with an outer Reed Solomon code to produce the convolutional encoded data.

FIGS. 10A and 10B are diagrams illustrating embodiments of a radio transmitter. This may involve the PMD module of a WLAN transmitter. In FIG. 10A, the baseband processing is shown to include a scrambler 172, channel encoder 174, interleaver 176, demultiplexer 170, a plurality of symbol mappers 180-184, a plurality of inverse fast Fourier transform (IFFT)/cyclic prefix addition modules 186-190 and a space/time encoder 192. The baseband portion of the transmitter may further include a mode manager module 175 that receives the mode selection signal 173 and produces settings 179 for the radio transmitter portion and produces the rate selection 171 for the baseband portion. In this embodiment, the scrambler 172, the channel encoder 174, and the interleaver 176 comprise an error protection module. The symbol mappers 180-184, the plurality of IFFT/cyclic prefix modules 186-190, the space time encoder 192 comprise a portion of the digital baseband processing module.

In operations, the scrambler 172 adds (e.g., in a Galois Finite Field (GF2)) a pseudo random sequence to the outbound data bits 88 to make the data appear random. A pseudo random sequence may be generated from a feedback shift register with the generator polynomial of S(x)=x⁷+x⁴+1 to produce scrambled data. The channel encoder 174 receives the scrambled data and generates a new sequence of bits with redundancy. This will enable improved detection at the receiver. The channel encoder 174 may operate in one of a plurality of modes. For example, for backward compatibility with IEEE 802.11(a) and IEEE 802.11(g), the channel encoder has the form of a rate 1/2 convolutional encoder with 64 states and a generator polynomials of G₀=133₈ and G₁=171₈. The output of the convolutional encoder may be punctured to rates of ½, ⅔, and ¾ according to the specified rate tables (e.g., tables 1-12). For backward compatibility with IEEE 802.11(b) and the CCK modes of IEEE 802.11(g), the channel encoder has the form of a CCK code as defined in IEEE 802.11(b). For higher data rates (such as those illustrated in tables 6, 8 and 10), the channel encoder may use the same convolution encoding as described above or it may use a more powerful code, including a convolutional code with more states, any one or more of the various types of error correction codes (ECCs) mentioned above (e.g., RS, LDPC, turbo, TTCM, etc.) a parallel concatenated (turbo) code and/or a low density parity check (LDPC) block code. Further, any one of these codes may be combined with an outer Reed Solomon code. Based on a balancing of performance, backward compatibility and low latency, one or more of these codes may be optimal. Note that the concatenated turbo encoding and low density parity check will be described in greater detail with reference to subsequent Figures.

The interleaver 176 receives the encoded data and spreads it over multiple symbols and transmit streams. This allows improved detection and error correction capabilities at the receiver. In one embodiment, the interleaver 176 will follow the IEEE 802.11(a) or (g) standard in the backward compatible modes. For higher performance modes (e.g., such as those illustrated in tables 6, 8 and 10), the interleaver will interleave data over multiple transmit streams. The demultiplexer 170 converts the serial interleave stream from interleaver 176 into M-parallel streams for transmission.

Each symbol mapper 180-184 receives a corresponding one of the M-parallel paths of data from the demultiplexer. Each symbol mapper 180-182 lock maps bit streams to quadrature amplitude modulated QAM symbols (e.g., BPSK, QPSK, 16 QAM, 64 QAM, 256 QAM, et cetera) according to the rate tables (e.g., tables 1-12). For IEEE 802.11(a) backward compatibility, double Gray coding may be used.

The map symbols produced by each of the symbol mappers 180-184 are provided to the IFFT/cyclic prefix addition modules 186-190, which performs frequency domain to time domain conversions and adds a prefix, which allows removal of inter-symbol interference at the receiver. Note that the length of the IFFT and cyclic prefix are defined in the mode tables of tables 1-12. In general, a 64-point IFFT will be used for 20 MHz channels and 128-point IFFT will be used for 40 MHz channels.

The space/time encoder 192 receives the M-parallel paths of time domain symbols and converts them into P-output symbols. In one embodiment, the number of M-input paths will equal the number of P-output paths. In another embodiment, the number of output paths P will equal 2M paths. For each of the paths, the space/time encoder multiples the input symbols with an encoding matrix that has the form of

$\begin{bmatrix} C_{1} & C_{2} & C_{3} & C_{4} & \ldots & C_{{2M} - 1} & C_{2M} \\ {- C_{2}^{*}} & C_{1}^{*} & {- C_{4}^{*}} & C_{3}^{*} & \ldots & {- C_{2M}^{*}} & C_{{2M} - 1} \end{bmatrix}.$

The rows of the encoding matrix correspond to the number of input paths and the columns correspond to the number of output paths.

FIG. 10B illustrates the radio portion of the transmitter that includes a plurality of digital filter/up-sampling modules 194-198, digital-to-analog conversion modules 200-204, analog filters 206-216, I/Q modulators 218-222, RF amplifiers 224-228, RF filters 230-234 and antennae 236-240. The P-outputs from the space/time encoder 192 are received by respective digital filtering/up-sampling modules 194-198. In one embodiment, the digital filters/up sampling modules 194-198 are part of the digital baseband processing module and the remaining components comprise the plurality of RF front-ends. In such an embodiment, the digital baseband processing module and the RF front end comprise a direct conversion module.

In operation, the number of radio paths that are active correspond to the number of P-outputs. For example, if only one P-output path is generated, only one of the radio transmitter paths will be active. As one of average skill in the art will appreciate, the number of output paths may range from one to any desired number.

The digital filtering/up-sampling modules 194-198 filter the corresponding symbols and adjust the sampling rates to correspond with the desired sampling rates of the digital-to-analog conversion modules 200-204. The digital-to-analog conversion modules 200-204 convert the digital filtered and up-sampled signals into corresponding in-phase and quadrature analog signals. The analog filters 206-214 filter the corresponding in-phase and/or quadrature components of the analog signals, and provide the filtered signals to the corresponding I/Q modulators 218-222. The I/Q modulators 218-222 based on a local oscillation, which is produced by a local oscillator 100, up-converts the I/Q signals into radio frequency signals.

The RF amplifiers 224-228 amplify the RF signals which are then subsequently filtered via RF filters 230-234 before being transmitted via antennae 236-240.

FIGS. 11A and 11B are diagrams illustrating embodiments of a radio receiver (as shown by reference numeral 250). These diagrams illustrate a schematic block diagram of another embodiment of a receiver. FIG. 11A illustrates the analog portion of the receiver which includes a plurality of receiver paths. Each receiver path includes an antenna, RF filters 252-256, low noise amplifiers 258-262, I/Q demodulators 264-268, analog filters 270-280, analog-to-digital converters 282-286 and digital filters and down-sampling modules 288-290.

In operation, the antennae receive inbound RF signals, which are band-pass filtered via the RF filters 252-256. The corresponding low noise amplifiers 258-262 amplify the filtered signals and provide them to the corresponding I/Q demodulators 264-268. The I/Q demodulators 264-268, based on a local oscillation, which is produced by local oscillator 100, down-converts the RF signals into baseband in-phase and quadrature analog signals.

The corresponding analog filters 270-280 filter the in-phase and quadrature analog components, respectively. The analog-to-digital converters 282-286 convert the in-phase and quadrature analog signals into a digital signal. The digital filtering and down-sampling modules 288-290 filter the digital signals and adjust the sampling rate to correspond to the rate of the baseband processing, which will be described in FIG. 11B.

FIG. 11B illustrates the baseband processing of a receiver. The baseband processing includes a space/time decoder 294, a plurality of fast Fourier transform (FFT)/cyclic prefix removal modules 296-300, a plurality of symbol demapping modules 302-306, a multiplexer 308, a deinterleaver 310, a channel decoder 312, and a descramble module 314. The baseband processing module may further include a mode managing module 175, which produces rate selections 171 and settings 179 based on mode selections 173. The space/time decoding module 294, which performs the inverse function of space/time encoder 192, receives P-inputs from the receiver paths and produce M-output paths. The M-output paths are processed via the FFT/cyclic prefix removal modules 296-300 which perform the inverse function of the IFFT/cyclic prefix addition modules 186-190 to produce frequency domain symbols.

The symbol demapping modules 302-306 convert the frequency domain symbols into data utilizing an inverse process of the symbol mappers 180-184. The multiplexer 308 combines the demapped symbol streams into a single path.

The deinterleaver 310 deinterleaves the single path utilizing an inverse function of the function performed by interleaver 176. The deinterleaved data is then provided to the channel decoder 312 which performs the inverse function of channel encoder 174. The descrambler 314 receives the decoded data and performs the inverse function of scrambler 172 to produce the inbound data 98.

FIG. 12 is a diagram illustrating an embodiment of an access point (AP) and multiple wireless local area network (WLAN) devices operating according to one or more various aspects and/or embodiments of the invention. The AP point 1200 may compatible with any number of communication protocols and/or standards, e.g., IEEE 802.11(a), IEEE 802.11(b), IEEE 802.11(g), IEEE 802.11(n), as well as in accordance with various aspects of invention. According to certain aspects of the present invention, the AP supports backwards compatibility with prior versions of the IEEE 802.11x standards as well. According to other aspects of the present invention, the AP 1200 supports communications with the WLAN devices 1202, 1204, and 1206 with channel bandwidths, MIMO dimensions, and at data throughput rates unsupported by the prior IEEE 802.11x operating standards. For example, the access point 1200 and WLAN devices 1202, 1204, and 1206 may support channel bandwidths from those of prior version devices and from 40 MHz to 1.28 GHz and above. The access point 1200 and WLAN devices 1202, 1204, and 1206 support MIMO dimensions to 4×4 and greater. With these characteristics, the access point 1200 and WLAN devices 1202, 1204, and 1206 may support data throughput rates to 1 GHz and above.

The AP 1200 supports simultaneous communications with more than one of the WLAN devices 1202, 1204, and 1206. Simultaneous communications may be serviced via OFDM tone allocations (e.g., certain number of OFDM tones in a given cluster), MIMO dimension multiplexing, or via other techniques. With some simultaneous communications, the AP 1200 may allocate one or more of the multiple antennae thereof respectively to support communication with each WLAN device 1202, 1204, and 1206, for example.

Further, the AP 1200 and WLAN devices 1202, 1204, and 1206 are backwards compatible with the IEEE 802.11(a), (b), (g), and (n) operating standards. In supporting such backwards compatibility, these devices support signal formats and structures that are consistent with these prior operating standards.

Generally, communications as described herein may be targeted for reception by a single receiver or for multiple individual receivers (e.g. via multi-user multiple input multiple output (MU-MIMO), and/or OFDMA transmissions, which are different than single transmissions with a multi-receiver address). For example, a single OFDMA transmission uses different tones or sets of tones (e.g., clusters or channels) to send distinct sets of information, each set of set of information transmitted to one or more receivers simultaneously in the time domain. Again, an OFDMA transmission sent to one user is equivalent to an OFDM transmission. A single MU-MIMO transmission may include spatially-diverse signals over a common set of tones, each containing distinct information and each transmitted to one or more distinct receivers. Some single transmissions may be a combination of OFDMA and MU-MIMO. MIMO transceivers illustrated may include SISO, SIMO, and MISO transceivers. The clusters employed for such communications may be continuous (e.g., adjacent to one another) or discontinuous (e.g., separated by a guard interval of band gap). Transmissions on different OFDMA clusters may be simultaneous or non-simultaneous. Such wireless communication devices as described herein may be capable of supporting communications via a single cluster or any combination thereof. Legacy users and new version users (e.g., TGac MU-MIMO, OFDMA, MU-MIMO/OFDMA, etc.) may share bandwidth at a given time or they can be scheduled at different times for certain embodiments.

FIG. 13 is a diagram illustrating an embodiment of a wireless communication device, and clusters, as may be employed for supporting communications with at least one additional wireless communication device. Generally speaking, a cluster may be viewed as a depiction of the mapping of tones, such as for an OFDM symbol, within or among one or more channels (e.g., sub-divided portions of the spectrum) that may be situated in one or more bands (e.g., portions of the spectrum separated by relatively larger amounts). As an example, various channels of 20 MHz may be situated within or centered around a 5 GHz band. The channels within any such band may be continuous (e.g., adjacent to one another) or discontinuous (e.g., separated by some guard interval or band gap). Oftentimes, one or more channels may be situated within a given band, and different bands need not necessarily have a same number of channels therein. Again, a cluster may generally be understood as any combination one or more channels among one or more bands.

The wireless communication device of this diagram may be of any of the various types and/or equivalents described herein (e.g., AP, WLAN device, or other wireless communication device including, though not limited to, any of those depicted in FIG. 1, etc.). The wireless communication device includes multiple antennae from which one or more signals may be transmitted to one or more receiving wireless communication devices and/or received from one or more other wireless communication devices.

Such clusters may be used for transmissions of signals via various one or more selected antennae. For example, different clusters are shown as being used to transmit signals respectively using different one or more antennae.

Also, it is noted that, with respect to certain embodiments, general nomenclature may be employed wherein a transmitting wireless communication device (e.g., such as being an Access point (AP), or a wireless station (STA) operating as an ‘AP’ with respect to other STAs) initiates communications, and/or operates as a network controller type of wireless communication device, with respect to a number of other, receiving wireless communication devices (e.g., such as being STAs), and the receiving wireless communication devices (e.g., such as being STAs) responding to and cooperating with the transmitting wireless communication device in supporting such communications. Of course, while this general nomenclature of transmitting wireless communication device(s) and receiving wireless communication device(s) may be employed to differentiate the operations as performed by such different wireless communication devices within a communication system, all such wireless communication devices within such a communication system may of course support bi-directional communications to and from other wireless communication devices within the communication system. In other words, the various types of transmitting wireless communication device(s) and receiving wireless communication device(s) may all support bi-directional communications to and from other wireless communication devices within the communication system. Generally speaking, such capability, functionality, operations, etc. as described herein may be applied to any wireless communication device.

Within certain wireless communication systems, wireless communication devices of various capabilities operate concurrently. For examples, legacy wireless communication devices (e.g., IEEE 802.11a, TGa and/or IEEE 802.11n, TGn compliant, or generally having a first capability) may operate in a common environment with newer wireless communication devices (e.g., IEEE 802.11ac, TGac compliant, or generally having a second capability). In such instances where various capability type wireless communication devices operate in a common vicinity or region, the legacy wireless communication devices (e.g., TGa and/or TGn compliant, first capability) should notified appropriately when communications corresponding to the newer wireless communication devices (e.g., TGac compliant, second capability) may be occurring or will occur. For examples, the legacy wireless communication devices (e.g., TGa and/or TGn compliant, first capability) may be notified regarding what types of communications will be contained within a remaining portion of a frame; such indication may be provided via a preamble of the frame. From one perspective, the preamble can indicate to the legacy wireless communication devices (e.g., TGa and/or TGn compliant, first capability) that they should stay off of the air (i.e., not access the communication medium) for some period of time in which communications when communications corresponding to the newer wireless communication devices (e.g., TGac compliant) may be occurring or will occur. Such newer types of communications may be orthogonal frequency division multiple access (OFDMA), multi-user multiple input multiple output (MU-MIMO), combination OFDMA/MU-MIMO, etc.

A phase rotation vector, as may be applied to such a preamble, provides for backward compatibility with the legacy wireless communication devices (e.g., TGa and/or TGn compliant, first capability) while allowing communications to be performed using newer protocols and recommended practices such as may be performed by newer wireless communication devices (e.g., TGac compliant, second capability). The bandwidth employed for legacy/first capability wireless communication devices can be narrower than newer/second capability wireless communication devices. For example, legacy/first capability wireless communication devices may operate using 20 MHz or 40 MHz (e.g., composed of two 20 MHz sub-bands) bandwidth, while newer/second capability wireless communication devices may operate using 80 MHz bandwidth (e.g., composed of four 20 MHz sub-bands or two 40 MHz sub-bands).

A phase rotation vector may be applied to the preamble to effectuate backward compatibility to accommodate the legacy/first capability wireless communication devices while also allowing function of the newer/second capability wireless communication devices.

For example, when considering the impact of certain phase rotation vectors as applied by or for legacy/first capability wireless communication devices (e.g., TGn compliant), there may be some potential risks of the legacy/first capability wireless communication devices (e.g., TGn compliant) not being able to perform carrier acquisition of the frames associated with the newer wireless communication devices (e.g., TGac compliant, second capability) if the phase rotation vector applied to the preambles is not designed properly. In some instances, a best legacy phase rotation vector may be employed by co-existed or co-located legacy wireless communication devices (e.g., TGn compliant, first capability).

A detailed peak to average power ratio (PAPR) analysis for a VHT frame may be performed. Generally speaking, a tradeoff is made between achieving a high degree of backward compatibility to accommodate the legacy/first capability wireless communication devices while also achieving a relatively low (e.g., acceptable) PAPR across the various fields of a frame. For example, ideally, there will not be a great deal of variation between the PAPR associated with the various fields of the frame when using an appropriately designed phase rotation vector.

Such a detailed PAPR analysis for a VHT frame provides for a decomposed PAPR comparison of different legacy preamble fields (e.g., a legacy short training field (L-STF), a legacy long training field (L-LTF), a legacy signal field (L-SIG), at least one very high throughput signal field (VHT-SIGA)) of VHT frames with different bandwidth options (20 MHz, 40 MHz, 80 MHz). Based on such detailed PAPR analysis, it is demonstrated that L-SIG & VHT-SIGA (as well as Non-HT Dup-Payload) are the dominant PAPRs across the VHT frame.

A novel means of effectuating PAPR reduction using an appropriately designed phase rotation vector is presented herein. Various options of such PAPR reduction techniques/proposals are compared and contrasted, and a novel, preferred embodiment of phase rotation vector design is presented herein that helps effectuate a great deal of PAPR reduction method without causing carrier detection problems for legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability).

FIG. 14 is a diagram illustrating an embodiment of phase rotation on a preamble as may be performed within one or more wireless communication devices. This diagram shows some of the possible deleterious effects that may be incurred by the application of a phase rotation vector on such legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability). For example, such legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) should be able to detect a 80 MHz legacy preamble and stay off of the air (i.e., not access the communication medium) for the entire packet duration so that the newer wireless communication devices (e.g., IEEE 802.11ac, TGac compliant, second capability) may operate without interference with those legacy wireless communication devices. As may be seen with respect to a 80 MHz frame (e.g., as employed by a newer wireless communication devices such as being IEEE 802.11ac, TGac compliant, second capability), the frame may be viewed as being composed of four separate 20 MHz sub-band components. Respective elements of a phase rotation vector may be applied to the respective sub-band components (e.g., 20 MHz each) of a preamble, shown as θ1, θ2, θ3, and θ4.

A certain level of backward compatibility should be maintained to avoid degrading the carrier detection/acquisition capability of the legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) that may operate using bandwidths of 20 MHz and 40 MHz.

As can be seen in the diagram, three possible options may be encountered when operating using a legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) using a bandwidth of 40 MHz, a 40 MHz sub-band may occupy a lower portion of the 80 MHz band, a 40 MHz sub-band may occupy an upper portion of the 80 MHz band, or a 40 MHz band associated with those wireless communication devices operating using a overlapped basic services set (OBSS) may overlap the second and third 20 MHz sub-bands of the 80 MHz band.

Mathematically, the most backward compatible 80 MHz phase rotation vector is simply [1, j, −1, −j] (i.e., [0, 90 deg, 180 deg, 270 deg]). However, such a phase rotation vector may actually lead to an undesirably high PAPR (e.g., shown with respect to FIG. 15 and FIG. 16).

A large PAPR variation among the various fields of a field can be problematic for a variety of reasons including operating within a non-linear region of a power amplifier (PA) or RF amplifier (e.g., as shown within various embodiments herein) implemented within a wireless communication device. A relatively large back-off (e.g., reduction in power) may be required to ensure operation within a linear region of such components within a wireless communication device.

Considering the backward compatibility design considerations with respect to legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability), certain considerations may be of significant concern including the processing such as performed by a receiving wireless communication device (RX) as related to legacy preamble decoding such as: carrier detection (CD), timing acquisition, channel estimation, carrier frequency offset (CFO) correction, L-SIG decode, etc.

To effectuate backward compatibility, an appropriately designed phase rotation vector should be transparent to all functions except for carrier detection (CD). For example, except “carrier detection”, all other processing operations should be transparent to the choice of per-20 MHz sub-band phase rotations (e.g., to the respective 20 MHz sub-band components within a preamble). For carrier detection (CD), the impact of phase rotation depends on the particular processing means being employed. For example, if an auto-correlation based processing means is employed, then carrier detection should also be transparent to arbitrary phase rotations. Alternatively, if a matched filter based detection processing means is employed, then depending on its location inside 80 MHz spectrum and the per-20 MHz sub-band phase rotation factors (e.g., applied to the respective 20 MHz sub-band components within a preamble), 40 MHz legacy/IEEE 802.11n devices might “see” a totally different legacy STF field than IEEE 802.11n frames. Such legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability), employing such a matched filter based detection processing means, typically will not be able to perform appropriate receiver processing and deal with such a situation.

FIG. 15 is a diagram illustrating an embodiment of a comparison of peak to average power ratio (PAPR) across various fields of a packet using various phase rotation vectors on frames of various bandwidths. As can be seen, various respective fields of a packet are affected differently and can have different respective PAPRs associated therewith. The fields L-SIG and VHT-SIGA (as well as Non-HT Dup Payload) are the dominant PAPRs across the VHT frame when using a phase rotation vector of [1, j] as associated with legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) using a bandwidth of 40 MHz, when using a phase rotation vector of [1, −1, −1, −1] as associated with newer wireless communication devices (e.g., IEEE 802.11ac, TGac compliant, second capability) using a bandwidth of 80 MHz, and when using a phase rotation vector of [1, j, −1, −j] as associated with newer wireless communication devices (e.g., IEEE 802.11ac, TGac compliant, second capability) using a bandwidth of 80 MHz.

As can be seen, the L-SIG PAPR is much higher than any other fields in 40 MHz and 80 MHz mode. It is also noted that all of these results are assuming a 4× over-sample. It is further noted that the PAPR numbers shown in the table for L-SIG, VHT-SIGA, VHT-SIGB and VHT-DATA fields are the 99.9-percentile PAPR. To be specific, 99.9% of the instantaneous time-domain OFDM signal power is less than this number when the average OFDM signal is normalized to be 1.

One manner to deal with this relatively large PAPR for this highest affected field is to employ a relatively large back-off; however, it may not be desirable to employ such a large back-off to deal only with a singularly problematic affected field.

FIG. 16 is a diagram illustrating an embodiment of a complementary cumulative density (or distribution) function (CCDF) of instantaneous power (P_(inst)) for the L-SIG field. As can be seen in this diagram, the phase rotation vector of [1, j, −1, −j] provides a relatively poor performance and could necessitate using a relatively large back-off. Such a relatively large back-off can severely limit the transmit power by which signals may be transmitted from a transmitting wireless communication device. That is to say, the transmit power must be reduced significantly (e.g., using a relatively large back-off) to transmit signals without distortion.

An appropriately designed PAPR technique is presented herein, as it generally is undesirable to apply a big PA/RF amplifier back-off only to satisfy one poorly performing field (e.g., L-SIG/VHT-SIGA). A better system design provides for more balanced PAPRs across the various fields of the packet. Such a better system design at least allows the payload field to be the dominant PAPR source.

Certain embodiment may require additional PA back-off simply to mitigate the effects of a larger than necessary L-SIG/VHT-SIGA PAPR. For example, in one embodiment, about 2.0 dB additional PA back-off is needed for 40 MHz L-SIG when compared to the payload field, and about 4.3 dB additional PA back-off is needed for 80 MHz L-SIG (e.g., if using [1, j, −1, −j] as phase rotation factors).

A good PAPR reduction technique also benefits non-HT DUP frames. Such non-HT DUP frames may be created using the same rule as legacy preamble (e.g., as defined in Section 20.3.11.11 of IEEE Std 802.11n™-2009 as incorporated by reference above). For such DUP frames, even the payload field may suffer deleteriously from a large PAPR.

FIG. 17 is a diagram illustrating an alternative embodiment of phase rotation on a preamble as may be performed within one or more wireless communication devices. This embodiment employs a phase rotation vector of [1, j, 1, j] and also employs a cyclic shift delay (CSD) of 25 ns to the upper 40 MHz sub-band component of the preamble. Such a phase rotation vector of [1, j, 1, j] (25 ns) does in fact improve the PAPR. However, the risk of potential carrier detection problem for legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) using a bandwidth of 40 MHz. While this approach does provide for some modest improvement in performance, a following embodiment provides for a much greater improvement in performance.

FIG. 18 is a diagram illustrating another embodiment of phase rotation on a preamble as may be performed within one or more wireless communication devices. A novel PAPR reduction method presented herein can be used to reduce the PAPR across the respective fields without changing L-STF as “seen” by legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) using a bandwidth of 40 MHz.

For example, since the L-STF tones are spaced by 1.25 MHz in the frequency domain (f-dom), multiples of 800 ns CSD as applied to the respective sub-band components of a preamble (e.g., no CSD applied to the first sub-band component, 800 ns CSD applied to the second sub-band component, 1600 ns CSD applied to the third sub-band component, and 2400 ns CSD applied to the fourth sub-band component in one embodiment). The application of such CSDs will not change the L-STF field at all. Hence, those legacy wireless communication devices (e.g., IEEE 802.11n, TGn compliant, first capability) using a bandwidth of 40 MHz will “see” the exact legacy L-STF as defined in accordance with IEEE 802.11n.

The multiples of 800 ns CSD can be implemented easily because there are only 4 possible phase rotation factors: 1, −1, j, −j. No additional hardware complexities are required for the implementation. It is noted that, except for the L-STF field (which is unaffected using these appropriately selected CSDs), other legacy preamble fields (L-LTF, L-SIG, VHT-SIGA) are not exactly copies of the 20 MHz corresponding fields with proper phase rotations.

FIG. 19 is a diagram illustrating another embodiment of a comparison of PAPR across various fields of a packet using various phase rotation vectors on frames of various bandwidths. As may be seen, the second row from the top and the bottom row employ a PAPR reduction method using integer multiples of a CSD being applied to the respective sub-band components of the preamble.

For example, the second row from the top [corresponding to a 40 MHz bandwidth] employs no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), 800 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”).

Also, the bottom row [corresponding to a 80 MHz bandwidth] employs no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), 800 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”), 1600 ns CSD applied to the third sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “−1”), and 2400 ns CSD applied to the fourth sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “−j”).

It is noted that the PAPR numbers shown in the table for L-SIG, VHT-SIGA, VHT-SIGB and VHT-DATA fields are the 99.9-percentile PAPR. To be specific, 99.9% of the instantaneous time-domain OFDM signal power is less than this number when the average OFDM signal is normalized to be 1.

FIG. 20 is a diagram illustrating another embodiment of a CCDF of P_(inst) for the L-SIG field. As can be seen when comparing the FIG. 20 with FIG. 16, by using the integer multiples of a CSD being applied to the respective sub-band components of the preamble (e.g., shown using the two curves whose data points are triangular shaped), a significant improvement in performance is achieved.

FIG. 21 is a diagram illustrating another embodiment of a CCDF of P_(inst) for the L-SIG field, and particularly, using 4× oversampling. This diagram is analogous with respect to previous embodiments, with at least one difference being that 4× oversampling is performed on signals before they are provided to a digital to analog converter (DAC) within a wireless communication device before being transmitted there from.

FIG. 22 is a diagram illustrating another embodiment of a comparison of PAPR across various fields of a packet using various phase rotation vectors on frames of various bandwidths.

As may be seen, the second row from the top, the third row from the top, and the bottom row employ a PAPR reduction method using integer multiples of a CSD being applied to the respective sub-band components of the preamble.

For example, the second row from the top [corresponding to a 40 MHz bandwidth] employs no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), 400 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”).

For example, the third row from the top [corresponding to a 40 MHz bandwidth] employs no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), 800 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”).

Also, the bottom row [corresponding to a 80 MHz bandwidth] employs no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), 800 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”), 1600 ns CSD applied to the third sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “−1”), and 2400 ns CSD applied to the fourth sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “−j”).

FIG. 23 is a diagram illustrating another embodiment of a CCDF of P_(inst) for the L-SIG field, and particularly, using 4× oversampling. As can be seen in this diagram, by using the integer multiples of a CSD being applied to the respective sub-band components of the preamble (e.g., shown using the two curves whose data points are triangular shaped, and shown using the one curve whose data points are diamond shaped), a significant improvement in performance is achieved.

The mathematical analysis associated with the PAPR reduction method is presented below.

1. No oversampled 40 MHz PAPR with phase rotation [1, j]

$\begin{matrix} {{x(n)} = {\sum\limits_{k = {- 64}}^{63}{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{128}}}}} \\ {= {\sum\limits_{k = {- 64}}^{- 1}\left( {{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{128}}} + {{X\left( {k + 64} \right)}^{\frac{{- j}\; 2\; \pi \; {({k + 64})}n}{128}}}} \right)}} \\ {= {\sum\limits_{k = {- 64}}^{- 1}\left( {{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{128}}} + {j\; {X(k)}^{\frac{{- j}\; 2\; \pi \; {({k + 64})}n}{128}}}} \right)}} \\ {= {\left( {\sum\limits_{k = {- 64}}^{- 1}{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{128}}}} \right)\left( {1 + {j}^{{- j}\; \pi \; n}} \right)}} \end{matrix}$

As can be seen, the term, (1+je^(−jm)), is a constant modulus term.

2. 4× oversampled 40 MHz PAPR with phase rotation [1, j]

$\begin{matrix} {{x(n)} = {\sum\limits_{k = {- 64}}^{63}{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{4 \times 128}}}}} \\ {= {\sum\limits_{k = {- 64}}^{- 1}\left( {{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{4 \times 128}}} + {{X\left( {k + 64} \right)}^{\frac{{- j}\; 2\; \pi \; {({k + 64})}n}{4 \times 128}}}} \right)}} \\ {= {\sum\limits_{k = {- 64}}^{- 1}\left( {{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{4 \times 128}}} + {j\; {X(k)}^{\frac{{- j}\; 2\; \pi \; {({k + 64})}n}{4 \times 128}}}} \right)}} \\ {= {\left( {\sum\limits_{k = {- 64}}^{- 1}{{X(k)}^{\frac{{- j}\; 2\; \pi \; {kn}}{4 \times 128}}}} \right)\left( {1 + {j}^{- \frac{j\; \pi \; n}{4}}} \right)}} \end{matrix}$

As can be seen, the term,

$\left( {1 + {j}^{- \frac{j\; \pi \; n}{4}}} \right),$

is a non-constant (i.e., not constant) modulus term.

FIG. 24 is a diagram illustrating an embodiment of Gaussian fit of a time-domain (t-dom) signal. As can be seen with respect to this diagram, by using the integer multiples of a CSD being applied to the respective sub-band components of the preamble (e.g., shown using the bottom two graphs), a significant improvement in performance is achieved.

FIG. 25 is a diagram illustrating an embodiment of a method for operating one or more wireless communication devices. Referring to method 2500 of FIG. 25, the method 2500 describes operations as may be performed within a transmitting wireless communication device. The method 2500 begins by applying elements of a phase rotation vector to respective sub-band components of a preamble, as shown in a block 2510.

The method 2500 continues by applying respective integer multiples of CSD to respective sub-band components of the preamble, as shown in a block 2520.

For example, the operations of the block 2520 may be effectuated by applying second CSD (e.g., 1×CSD_(X ns)) to second sub-band component of the preamble, as shown in a block 2520 a. Such operations may continue by applying second CSD (e.g., 1×CSD_(X ns)) to second sub-band component of the preamble, as shown in a block 2520 b. Generally speaking, the operations may continue by applying n^(th) CSD (e.g., (n−1)×CSD_(X ns)) to n^(th) sub-band component of the preamble, as shown in a block 2520 c.

For example, one embodiment operates by processing a preamble [corresponding to a 80 MHz bandwidth] by employing no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), 800 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”), 1600 ns CSD applied to the third sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “−1”), and 2400 ns CSD applied to the fourth sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “−j”).

Another embodiment operates by processing a preamble [corresponding to a 40 MHz bandwidth] by employing no CSD applied to the first sub-band component of 20 MHz (rotated by an element of a phase rotation vector of “1”), and 800 ns CSD applied to the second sub-band component of 20 MHz (rotated by an element of the phase rotation vector of “j”).

Generally, the principles of applying integer multiples of a CSD to the respective sub-band components of the preamble may be applied to preambles of various sizes without departing from the scope and spirit of the invention.

It is also noted that the various operations and functions as described with respect to various methods herein may be performed within a wireless communication device, such as using a baseband processing module and/or a processing module implemented therein (e.g., such as in accordance with the baseband processing module 64 and/or the processing module 50 as described with reference to FIG. 2) and/or other components therein.

For example, such a baseband processing module can perform processing of various signals including applying any of a variety of phase rotation vectors to preambles of signals and applying respective integer multiples of cyclic shift delays (CSDs) to respective sub-band components of the preamble, or any other operations and functions as described herein, etc. or their respective equivalents. In some embodiments, such a baseband processing module and/or a processing module (which may be implemented in the same device or separate devices) can perform such processing to generate signals for transmission using at least one of any number of radios and at least one of any number of antennae of another wireless communication device in accordance with various aspects of the invention, and/or any other operations and functions as described herein, etc. or their respective equivalents. In some embodiments, such processing is performed cooperatively by a processing module in a first device, and a baseband processing module within a second device. In other embodiments, such processing is performed wholly by a baseband processing module.

It is also noted that the various operations and functions as described with respect to various methods herein may be performed within a wireless communication device, such as using a baseband processing module and/or a processing module implemented therein, (e.g., such as in accordance with the baseband processing module 64 and/or the processing module 50 as described with reference to FIG. 2) and/or other components therein. For example, such a baseband processing module can generate such signals and frames as described herein as well as perform various operations and analyses as described herein, or any other operations and functions as described herein, etc. or their respective equivalents.

For example, such a baseband processing module and/or a processing module (which may be implemented in the same device or separate devices) can perform generation of a beamforming feedback frame, as well as generation of a signal including such a beamforming feedback frame and transmission of that signal using at least one of any number of radios and at least one of any number of antennae of a wireless communication device in accordance with various aspects of the invention, and/or any other operations and functions as described herein, etc. or their respective equivalents. In some embodiments, such a beamforming feedback frame is generated cooperatively by a processing module in a first device, and a baseband processing module within a second device. In other embodiments, such a beamforming feedback frame is generated wholly by a baseband processing module or a processing module.

In some embodiments, such a baseband processing module and/or a processing module (which may be implemented in the same device or separate devices) can perform such processing to generate signals for transmission using at least one of any number of radios and at least one of any number of antennae to another wireless communication device (e.g., which also may include at least one of any number of radios and at least one of any number of antennae) in accordance with various aspects of the invention, and/or any other operations and functions as described herein, etc. or their respective equivalents. In some embodiments, such processing is performed cooperatively by a processing module in a first device, and a baseband processing module within a second device. In other embodiments, such processing is performed wholly by a baseband processing module or a processing module.

As may be used herein, the terms “substantially” and “approximately” provides an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to fifty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. Such relativity between items ranges from a difference of a few percent to magnitude differences. As may also be used herein, the term(s) “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. As may even further be used herein, the term “operable to” or “operably coupled to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform, when activated, one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item. As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater magnitude than signal 2, a favorable comparison may be achieved when the magnitude of signal 1 is greater than that of signal 2 or when the magnitude of signal 2 is less than that of signal 1.

As may also be used herein, the terms “processing module”, “module”, “processing circuit”, and/or “processing unit” (e.g., including various modules and/or circuitries such as may be operative, implemented, and/or for encoding, for decoding, for baseband processing, etc.) may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module, module, processing circuit, and/or processing unit may have an associated memory and/or an integrated memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of the processing module, module, processing circuit, and/or processing unit. Such a memory device may be a read-only memory (ROM), random access memory (RAM), volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module, module, processing circuit, and/or processing unit includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that if the processing module, module, processing circuit, and/or processing unit implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element may store, and the processing module, module, processing circuit, and/or processing unit executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in one or more of the Figures. Such a memory device or memory element can be included in an article of manufacture.

The present invention has been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claimed invention. Further, the boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality. To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claimed invention. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof.

The present invention may have also been described, at least in part, in terms of one or more embodiments. An embodiment of the present invention is used herein to illustrate the present invention, an aspect thereof, a feature thereof, a concept thereof, and/or an example thereof. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process that embodies the present invention may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones.

Unless specifically stated to the contra, signals to, from, and/or between elements in a figure of any of the figures presented herein may be analog or digital, continuous time or discrete time, and single-ended or differential. For instance, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more particular architectures are described herein, other architectures can likewise be implemented that use one or more data buses not expressly shown, direct connectivity between elements, and/or indirect coupling between other elements as recognized by one of average skill in the art.

The term “module” is used in the description of the various embodiments of the present invention. A module includes a functional block that is implemented via hardware to perform one or module functions such as the processing of one or more input signals to produce one or more output signals. The hardware that implements the module may itself operate in conjunction software, and/or firmware. As used herein, a module may contain one or more sub-modules that themselves are modules.

While particular combinations of various functions and features of the present invention have been expressly described herein, other combinations of these features and functions are likewise possible. The present invention is not limited by the particular examples disclosed herein and expressly incorporates these other combinations.

Mode Selection Tables:

TABLE 1 2.4 GHz, 20/22 MHz channel BW, 54 Mbps max bit rate Code Rate Modulation Rate NBPSC NCBPS NDBPS EVM Sensitivity ACR AACR 1 Barker BPSK 2 Barker QPSK 5.5 CCK 6 BPSK 0.5 1 48 24 −5 −82 16 32 9 BPSK 0.75 1 48 36 −8 −81 15 31 11 CCK 12 QPSK 0.5 2 96 48 −10 −79 13 29 18 QPSK 0.75 2 96 72 −13 −77 11 27 24 16-QAM 0.5 4 192 96 −16 −74 8 24 36 16-QAM 0.75 4 192 144 −19 −70 4 20 48 64-QAM 0.666 6 288 192 −22 −66 0 16 54 64-QAM 0.75 6 288 216 −25 −65 −1 15

TABLE 2 Channelization for Table 1 Frequency Channel (MHz) 1 2412 2 2417 3 2422 4 2427 5 2432 6 2437 7 2442 8 2447 9 2452 10 2457 11 2462 12 2467

TABLE 3 Power Spectral Density (PSD) Mask for Table 1 PSD Mask 1 Frequency Offset dBr −9 MHz to 9 MHz  0 +/−11 MHz −20 +/−20 MHz −28 +/−30 MHz and −50 greater

TABLE 4 5 GHz, 20 MHz channel BW, 54 Mbps max bit rate Code Rate Modulation Rate NBPSC NCBPS NDBPS EVM Sensitivity ACR AACR 6 BPSK 0.5 1 48 24 −5 −82 16 32 9 BPSK 0.75 1 48 36 −8 −81 15 31 12 QPSK 0.5 2 96 48 −10 −79 13 29 18 QPSK 0.75 2 96 72 −13 −77 11 27 24 16-QAM 0.5 4 192 96 −16 −74 8 24 36 16-QAM 0.75 4 192 144 −19 −70 4 20 48 64-QAM 0.666 6 288 192 −22 −66 0 16 54 64-QAM 0.75 6 288 216 −25 −65 −1 15

TABLE 5 Channelization for Table 4 Frequency Frequency Channel (MHz) Country Channel (MHz) Country 240 4920 Japan 244 4940 Japan 248 4960 Japan 252 4980 Japan 8 5040 Japan 12 5060 Japan 16 5080 Japan 36 5180 USA/Europe 34 5170 Japan 40 5200 USA/Europe 38 5190 Japan 44 5220 USA/Europe 42 5210 Japan 48 5240 USA/Europe 46 5230 Japan 52 5260 USA/Europe 56 5280 USA/Europe 60 5300 USA/Europe 64 5320 USA/Europe 100 5500 USA/Europe 104 5520 USA/Europe 108 5540 USA/Europe 112 5560 USA/Europe 116 5580 USA/Europe 120 5600 USA/Europe 124 5620 USA/Europe 128 5640 USA/Europe 132 5660 USA/Europe 136 5680 USA/Europe 140 5700 USA/Europe 149 5745 USA 153 5765 USA 157 5785 USA 161 5805 USA 165 5825 USA

TABLE 6 2.4 GHz, 20 MHz channel BW, 192 Mbps max bit rate TX ST Anten- Code Code Rate nas Rate Modulation Rate NBPSC NCBPS NDBPS 12 2 1 BPSK 0.5 1 48 24 24 2 1 QPSK 0.5 2 96 48 48 2 1 16-QAM 0.5 4 192 96 96 2 1 64-QAM 0.666 6 288 192 108 2 1 64-QAM 0.75 6 288 216 18 3 1 BPSK 0.5 1 48 24 36 3 1 QPSK 0.5 2 96 48 72 3 1 16-QAM 0.5 4 192 96 144 3 1 64-QAM 0.666 6 288 192 162 3 1 64-QAM 0.75 6 288 216 24 4 1 BPSK 0.5 1 48 24 48 4 1 QPSK 0.5 2 96 48 96 4 1 16-QAM 0.5 4 192 96 192 4 1 64-QAM 0.666 6 288 192 216 4 1 64-QAM 0.75 6 288 216

TABLE 7 Channelization for Table 6 Channel Frequency (MHz) 1 2412 2 2417 3 2422 4 2427 5 2432 6 2437 7 2442 8 2447 9 2452 10 2457 11 2462 12 2467

TABLE 8 5 GHz, 20 MHz channel BW, 192 Mbps max bit rate TX ST Anten- Code Code Rate nas Rate Modulation Rate NBPSC NCBPS NDBPS 12 2 1 BPSK 0.5 1 48 24 24 2 1 QPSK 0.5 2 96 48 48 2 1 16-QAM 0.5 4 192 96 96 2 1 64-QAM 0.666 6 288 192 108 2 1 64-QAM 0.75 6 288 216 18 3 1 BPSK 0.5 1 48 24 36 3 1 QPSK 0.5 2 96 48 72 3 1 16-QAM 0.5 4 192 96 144 3 1 64-QAM 0.666 6 288 192 162 3 1 64-QAM 0.75 6 288 216 24 4 1 BPSK 0.5 1 48 24 48 4 1 QPSK 0.5 2 96 48 96 4 1 16-QAM 0.5 4 192 96 192 4 1 64-QAM 0.666 6 288 192 216 4 1 64-QAM 0.75 6 288 216

TABLE 9 channelization for Table 8 Frequency Frequency Channel (MHz) Country Channel (MHz) Country 240 4920 Japan 244 4940 Japan 248 4960 Japan 252 4980 Japan 8 5040 Japan 12 5060 Japan 16 5080 Japan 36 5180 USA/Europe 34 5170 Japan 40 5200 USA/Europe 38 5190 Japan 44 5220 USA/Europe 42 5210 Japan 48 5240 USA/Europe 46 5230 Japan 52 5260 USA/Europe 56 5280 USA/Europe 60 5300 USA/Europe 64 5320 USA/Europe 100 5500 USA/Europe 104 5520 USA/Europe 108 5540 USA/Europe 112 5560 USA/Europe 116 5580 USA/Europe 120 5600 USA/Europe 124 5620 USA/Europe 128 5640 USA/Europe 132 5660 USA/Europe 136 5680 USA/Europe 140 5700 USA/Europe 149 5745 USA 153 5765 USA 157 5785 USA 161 5805 USA 165 5825 USA

TABLE 10 5 GHz, with 40 MHz channels and max bit rate of 486 Mbps TX ST Code Code Rate Antennas Rate Modulation Rate NBPSC 13.5 Mbps 1 1 BPSK 0.5 1 27 Mbps 1 1 QPSK 0.5 2 54 Mbps 1 1 16-QAM 0.5 4 108 Mbps 1 1 64-QAM 0.666 6 121.5 Mbps 1 1 64-QAM 0.75 6 27 Mbps 2 1 BPSK 0.5 1 54 Mbps 2 1 QPSK 0.5 2 108 Mbps 2 1 16-QAM 0.5 4 216 Mbps 2 1 64-QAM 0.666 6 243 Mbps 2 1 64-QAM 0.75 6 40.5 Mbps 3 1 BPSK 0.5 1 81 Mbps 3 1 QPSK 0.5 2 162 Mbps 3 1 16-QAM 0.5 4 324 Mbps 3 1 64-QAM 0.666 6 365.5 Mbps 3 1 64-QAM 0.75 6 54 Mbps 4 1 BPSK 0.5 1 108 Mbps 4 1 QPSK 0.5 2 216 Mbps 4 1 16-QAM 0.5 4 432 Mbps 4 1 64-QAM 0.666 6 486 Mbps 4 1 64-QAM 0.75 6

TABLE 11 Power Spectral Density (PSD) mask for Table 10 PSD Mask 2 Frequency Offset dBr −19 MHz to 19 MHz  0 +/−21 MHz −20 +/−30 MHz −28 +/−40 MHz and −50 greater

TABLE 12 Channelization for Table 10 Frequency Frequency Channel (MHz) Country Channel (MHz) County 242 4930 Japan 250 4970 Japan 12 5060 Japan 38 5190 USA/Europe 36 5180 Japan 46 5230 USA/Europe 44 5520 Japan 54 5270 USA/Europe 62 5310 USA/Europe 102 5510 USA/Europe 110 5550 USA/Europe 118 5590 USA/Europe 126 5630 USA/Europe 134 5670 USA/Europe 151 5755 USA 159 5795 USA 

What is claimed is:
 1. An apparatus, comprising: a baseband processing module for: applying a plurality of elements of a phase rotation vector respectively to a plurality of sub-band components of a preamble such that each of the plurality of elements of the phase rotation vector is applied to a respective one of the plurality of sub-band components of the preamble thereby generating a first modified preamble; and applying a plurality of integer multiples of a cyclic shift delay (CSD) respectively to the plurality of sub-band components of the first modified preamble such that each of the plurality of integer multiples of the CSD is applied to a respective one of the plurality of sub-band components of the first modified preamble thereby generating a second modified preamble; and a radio for transmitting a signal corresponding to the second modified preamble to a wireless communication device via at least one antenna; and wherein: each of the plurality of sub-band components of the preamble having a common, uniform bandwidth; and the phase rotation vector and the plurality of integer multiples of the CSD operative for minimizing a peak to average power ratio (PAPR) between a legacy short training field (L-STF) and at least one additional field within the second modified preamble.
 2. The apparatus of claim 1, wherein: the phase rotation vector being [1, j]; and the baseband processing module for: applying a first CSD of 0 ns to a first sub-band component of the first modified preamble; and applying a second CSD of 800 ns to a second sub-band component of the first modified preamble.
 3. The apparatus of claim 1, wherein: the phase rotation vector being [1, j, −1, −j]; and the baseband processing module for: applying a first CSD of 0 ns to a first sub-band component of the first modified preamble; applying a second CSD of 800 ns to a second sub-band component of the first modified preamble; applying a third CSD of 1600 ns to a third sub-band component of the first modified preamble; and applying a fourth CSD of 2400 ns to a fourth sub-band component of the first modified preamble.
 4. A method for operating a wireless communication device, the method comprising: applying a plurality of elements of a phase rotation vector respectively to a plurality of sub-band components of a preamble such that each of the plurality of elements of the phase rotation vector is applied to a respective one of the plurality of sub-band components of the preamble thereby generating a first modified preamble; applying a plurality of integer multiples of a cyclic shift delay (CSD) respectively to the plurality of sub-band components of the first modified preamble such that each of the plurality of integer multiples of the CSD is applied to a respective one of the plurality of sub-band components of the first modified preamble thereby generating a second modified preamble; and via at least one antenna of the wireless communication device, transmitting a signal corresponding to the second modified preamble to at least one additional wireless communication device.
 5. The method of claim 4, further comprising: applying a first CSD of 0 ns to a first sub-band component of the first modified preamble; and applying a second CSD of 800 ns to a second sub-band component of the first modified preamble.
 6. The method of claim 4, wherein: the phase rotation vector being [1, j].
 7. The method of claim 4, further comprising: applying a first CSD of 0 ns to a first sub-band component of the first modified preamble; applying a second CSD of 800 ns to a second sub-band component of the first modified preamble; applying a third CSD of 1600 ns to a third sub-band component of the first modified preamble; and applying a fourth CSD of 2400 ns to a fourth sub-band component of the first modified preamble.
 8. The method of claim 4, wherein: the phase rotation vector being [1, j, −1, −j].
 9. The method of claim 4, wherein: each of the plurality of sub-band components of the preamble having a common, uniform bandwidth.
 10. The method of claim 4, wherein: the phase rotation vector and the plurality of integer multiples of the CSD operative for minimizing a peak to average power ratio (PAPR) between a legacy short training field (L-STF) and at least one additional field within the second modified preamble.
 11. The method of claim 4, wherein: the wireless communication device being an access point (AP); and the at least one additional wireless communication device being a wireless station (STA).
 12. The method of claim 4, wherein: the wireless communication device being a first wireless station (STA); and the at least one additional wireless communication device being a second STA.
 13. An apparatus, comprising: a baseband processing module for: applying a plurality of elements of a phase rotation vector respectively to a plurality of sub-band components of a preamble such that each of the plurality of elements of the phase rotation vector is applied to a respective one of the plurality of sub-band components of the preamble thereby generating a first modified preamble; and applying a plurality of integer multiples of a cyclic shift delay (CSD) respectively to the plurality of sub-band components of the first modified preamble such that each of the plurality of integer multiples of the CSD is applied to a respective one of the plurality of sub-band components of the first modified preamble thereby generating a second modified preamble; and a radio for transmitting a signal corresponding to the second modified preamble to a wireless communication device via at least one antenna.
 14. The apparatus of claim 13, wherein the baseband processing module for: applying a first CSD of 0 ns to a first sub-band component of the first modified preamble; and applying a second CSD of 800 ns to a second sub-band component of the first modified preamble.
 15. The apparatus of claim 13, wherein: the phase rotation vector being [1, j].
 16. The apparatus of claim 13, wherein the baseband processing module for: applying a first CSD of 0 ns to a first sub-band component of the first modified preamble; applying a second CSD of 800 ns to a second sub-band component of the first modified preamble; applying a third CSD of 1600 ns to a third sub-band component of the first modified preamble; and applying a fourth CSD of 2400 ns to a fourth sub-band component of the first modified preamble.
 17. The apparatus of claim 13, wherein: the phase rotation vector being [1, j, −1, −j].
 18. The apparatus of claim 13, wherein: each of the plurality of sub-band components of the preamble having a common, uniform bandwidth.
 19. The apparatus of claim 13, wherein: the phase rotation vector and the plurality of integer multiples of the CSD operative for minimizing a peak to average power ratio (PAPR) between a legacy short training field (L-STF) and at least one additional field within the second modified preamble.
 20. The apparatus of claim 13, wherein: the apparatus being an access point (AP); and the wireless communication device being a wireless station (STA).
 21. The apparatus of claim 13, wherein: the apparatus being a first wireless station (STA); and the wireless communication device being a second STA. 